The preferred embodiment concerns an electrographic printing or copying device and in particular the cleaning of an applicator element that feeds toner to a photoconductor element. The preferred embodiment also concerns a method for operation of such a cleaning device.
A known device for cleaning of carrier elements in printers or copiers (DE 101 52 892 A1) comprise applicator rollers, photoconductor drums, transfer belts or photoconductor belts that are cleaned with magnetic roller arrangements. The surfaces of the rollers, drums or belts should be cleaned of toner with these magnetic roller arrangements.
In the known device a toner mixture made up of carrier particles and toner particles is supplied to an applicator roller via a magnetic roller arrangement. The applicator roller then transfers the toner particles onto a photoconductor corresponding to the characters to be printed. The toner remaining on the applicator roller and not transferred onto the photoconductor is removed from the surface of the applicator roller with a second magnetic roller arrangement. For this what is known as a magnetic brush is generated by the second magnetic roller arrangement, which magnetic brush brushes the still-remaining toner from the surface of the applicator roller with the aid of magnetic carrier particles arranged like beads. The toner mixture is then directed away from the applicator roller via rotation of the outer magnetic roller and fed again to a reservoir for toner mixture.
A device for transport of toner is known from the U.S. Pat. No. 4,647,179. The toner should thereby be applied on a photoconductor element in a developer station. For this charged toner particles are transported from a reservoir vessel to a traveling field device. The traveling field device comprises a plurality of spaced, linear electrodes that are connected with an alternating voltage source. Phase offset voltages are applied to the successive electrodes such that a progressive alternating electrostatic field arises. Toner particles are moved along the progression direction to the photoconductor element via this alternating field and the toner particles are drawn onto the photoconductor element via the corresponding oppositely charged photoconductor element.
For cleaning of the photoconductor element a vacuum sucker is provided that sucks the toner particles from the photoconductor element. In the known devices the toner is significantly damaged upon cleaning of the applicator elements since it is severely mechanically stressed in the cleaning, either due to the suction or by the brushing.
In a further known electrographic printing or copying device (DE 197 30 729 A1), toner is removed from a photoconductor belt by means of a cleaning device. The toner is thereby electrically and mechanically removed by the cleaning device. The cleaning device is a roller that rotates. The cleaning device is additionally connected to a direct voltage source whose voltage is set between 200 and 1000 V dependent on the toner quantity on the photoconductor belt. The transport of the toner away thereby occurs via rotation of the cleaning device, whereby the transfer onto the roller is assisted by the voltage.
The cleaning device comprises a cylindrical fur brush that rotates counter to the rotation direction of the photoconductor drum and thereby mechanically removes the toner from the photoconductor drum. A cleaning blade supports the removal of the toner from the photoconductor drum. A beating rod removes the toner from the fur brush and allows it to fall into a toner discharge screw. From there the toner is mechanically transported away.
Here an electromechanical cleaning also occurs, which is disadvantageous due to the wear.